Method And System For Obtaining Geochemistry Information From Pyrolysis Induced By Laser Induced Breakdown Spectroscopy

Abstract

A method for determining geochemistry of at least one geological sample with laser-induced breakdown spectral measurements performed on the geological sample in a time variant manner with spectral acquisitions made after each of a plurality of measurement shots, spectral pre-processing performed as necessary, and subsequent analysis is applied to the collected data to determine at least one geochemistry parameter of the sample. The method can provide a rapid method to estimate thermal maturity of a sample, which does not require sample preparation, and which can be non-destructive with respect to portions of the sample. A system for performing the method also is provided.

Description

[0001]This application claims the benefit under 35 U.S.C. §119(e) of prior U.S. Provisional Patent Application No. 62 / 038,950, filed Aug. 19, 2014 and U.S. Provisional Patent Application No. 62 / 150,860, filed Apr. 22, 2015, which are incorporated in their entirety by reference herein.FIELD OF THE INVENTION[0002]The present invention relates to a method for obtaining geochemistry information on geological samples or other types of samples and, more particularly, to a method for obtaining geochemistry information on geological materials with laser induced breakdown spectroscopy (LIBS). The present invention also relates to systems for the methods.BACKGROUND OF THE INVENTION[0003]Characterisation of source rocks is important for evaluation of both conventional and unconventional reservoirs. Organic matter is deposited and preserved at the bottom of lakes, seas and deltas. As more material is deposited, the organic matter is buried and the heat and pressure of burial transforms the orga...

AI Technical Summary

Benefits of technology

The present invention is a method and system for analyzing geological materials using laser light. The method involves subjecting the material to multiple measurement shots of laser light, which vaporizes a portion of the material and causes spectral emission. The spectral emission is detected, and the data is optionally pre-processed and analyzed. The system includes a laser, a detector, and a pre-processing device. The invention also includes a method for determining geochemistry parameters from the laser-induced plasma (LIBS) data. The technical effects of the invention include improved accuracy and precision in analyzing geological materials and the ability to determine reaction rates and activation energy distribution in the material.

Problems solved by technology

Therefore, any spatial information regarding the distribution of organic matter is lost during the crushing process.

They are also, practically, completely destructive with respect to the samples, as the samples cannot be used for further tests after programmed pyrolysis.

Programmed pyrolysis measurements are time intensive, usually requiring about an hour per sample to perform.

The results also can have issues with interference from carbonate in the sample.

This can be unreliable, as the Tmax peaks are often quite broad, such that the exact location of the peak can vary and can be difficult to reproduce with subsequent measurements.

Thermal maturity calculations from Tmax are often unreliable particularly for low organic content samples.

As programmed pyrolysis methods take approximately an hour per sample, this is a time intensive method to measure thermal maturity.

Predictive ability of FTIR to date for hydrogen and oxygen indices, however, has been of poor quality.

FTIR suffers the same drawback of loss of spatial resolution of the organic matter as the programmed pyrolysis, as samples need to be powdered before measurement.

The signal quality improves with larger spot size, but sacrifices resolution.

While a small amount of sample is consumed, the amount is so small that it is considered to be negligible and the technique is considered non-destructive.

LIBS does have a disadvantage in terms of quantification of heavier elements compared to XRF.

Further, those LIPS methods appear to be limited to just total organic carbon (TOC), and do not appear to present information on thermal maturity or kerogen versus bitumen discrimination.

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